Getting Internal Error

ArduCopter Copter 4.1
1

Hello everyone.
When my hexacopter was flying in guided mode, it suddenly rolled more than 60 degrees which could have resulted in a crash!
I got the following error after this flight:
“internal errors 0x400 I:799 cnstring_nan”
Cube V5+ with NEO 3 pro-GNSS.
Does anyone know anything about this?

Here is my log:

2

Can anyone help me please?

3

Update to latest Stable firmware. Post again if the issue persists.